The acronyms used herein shall have the following meanings:
Ack—Acknowledge
BS—Base Station
BSC—Base Station Controller
CAMEL—Customized Applications for Mobile Network Enhanced Logic
DP—Detection Point
GMSC—Gateway Mobile Switching Center
GSM—Global System for Mobile Communications
HLR—Home Location Register
IAM—Initial Address Message
IDP—Initial Detection Point
IN—Intelligent Network
ISUP—ISDN User Part
IXC—Inter Exchange Carrier
LEC—Local Exchange Carrier
MAP—Mobile Application Part
MSC—Mobile Switching Center
MSISDN—Mobile Station International Subscriber Directory Number
MSRN—Mobile Subscriber Roaming Number
MTP—Message Transport Part
PSAP—Public Safety Answering Point
RRB—Request Report BCSM Event
SCCP—Signaling Connection and Control Part
SCP—Service Control Point
SDP—Service Data Point
SSF—Service Switching Function
SK—Service Key
SP—Signaling Point
SRI—Send Routing Information
SSF—Service switching Function
T-CSI—Terminating CAMEL Subscription Information
VLR—Visitor Location Register
V—MSC Visiting MSC
VoIP—Voice over Internet Protocol
Public Safety Answering Points (PSAPs), also known as 911 call centers, are the public's first line of contact with public safety authorities in an emergency situation. The term “911” shall not be construed as being limited to calls signaled using the digits “911” as these digits are used to generically refer to any signaling to an emergency call center. Dialing 911 from a terminal quickly connects callers to a PSAP dispatcher. In the event a 911 call from a terminal is dropped or cut-off, it is standard procedure for the PSAP dispatcher to attempt to re-establish the connection with the terminal of the 911 caller by calling the same number received in the 911 call report.
However, there are situations where a PSAP or 911 call center may have difficulty re-establishing the connection with the terminal of the 911 caller, particularly if the terminal of the 911 caller is subscribed to IN services, due to restrictions that are placed on the IN subscriber side. Such restrictions may include parental control restrictions, insufficient pre-paid credit or available minutes. In such case, the terminal of the IN subscriber may be restricted in making or receiving calls to and from certain numbers even though the subscriber service is still active. For example, a terminal of a IN subscriber may be allowed to make certain outgoing calls, such as to a customer care number, 911 or certain 1-800 numbers or receive incoming calls, such as from 611, certain 1-800 numbers, and numbers that are always allowed or that are free of charge.
FIG. 1A illustrates a dropped 911 call 101 made from a terminal 102 subscribed to IN services, the call initially having been routed from terminal 102, to BS 103 through BSC 104 and MSC/VLR 105 to PSAP 106. FIG. 1B is a message flow diagram 100B illustrating the problem of a dropped 911 call made from a terminal of a subscriber to IN services. FIG. 1C is a message flow diagram 100C illustrating an attempted call back to a 911 caller with IN services. But the PSAP will not be able to connect successfully with 911 Caller (B party) in case of various called Party IN services restrictions. E.g. insufficient pre-paid money or minutes, parental restrictions etc. Due to these various IN service restrictions Service does not allow the PSAP call to IN subscriber.
Conventionally, there is no method or system to allow a PSAP to re-establish a connection to a terminal of a 911 caller who is an IN subscriber in the event of a dropped call, if there are restrictions on the terminal of the subscriber as herein before described. Because PSAP numbers are numerous and unregulated, there is no method or system to distinguish a PSAP number for such callback purposes. Also, there is no method to identify the calls from PSAP numbers and tag them separately to allow the calls to be connected free of charge to the 911 caller.
In the event a terminal of a subscriber to an IN service has a parental control, the parent may only allow the terminal held by the child to receive calls from green listed numbers, which are calls from e.g., parents, relatives, or close friends, whereas calls from other numbers, such as a PSAP, may be red-listed or barred. Finally, the IN service could be configured to apply a time restriction on the connection of calls during certain periods of time or days of the week. For example, a parent might block incoming and/or outgoing calls to a terminal held by a child during school hours from Monday to Friday. These time restrictions may inhibit a PSAP from calling back a terminal of a 911 caller.
What is desired is a method and system for connecting a PSAP or 911 call center to a terminal of an IN subscriber without restriction.